The present invention concerns fixing arrangements for electrostatic copying machines, serving to fuse the toner image transferred onto the upper (i.e., toner-image-bearing) face of a copy paper from an intermediate image carrier, e.g., a rotating copying drum. Fixing arrangements of the type in question comprise a heated plate serving to warm the lower face of the copy paper (i.e., the face not bearing the toner image) and also transport means for transporting the toner-image-bearing copy paper, or other such copy stock, through the fixing arrangement.
With known fixing arrangements of this particular type--e.g., that disclosed in U.S. Pat. No. 3,187,162, but that one merely by way of example--it is in general attempted to assure sufficient heat-transferring surface contact between the lower face of the copy paper and the upper surface of the heating plate by, in particular, making the upper surface of the heating plate as perfectly smooth as possible.
However, it has been found that even this expedient can lead to non-uniforming heating action, when resort is had to various conventional techniques for pressing the copy paper against the heating plate. The result of non-uniform heating action is non-uniforming fixing or fusing of different portions of the toner image, some portions of the toner image being excessively fixed and others insufficiently fixed. This is visually perceivable in the final copy in a non-uniform quality or character of image.